In a bitterly contested intraparty vote, Waxman, 69, Thursday ousted the 82-year-old dean of the House, John Dingell of Michigan, as chairman of the committee, which originates much of Congress’ energy and environmental legislation.

Waxman’s new role adds another worry for an oil and gas industry already confronting a severe recession, plunging crude prices and a Democratic administration committed to limiting greenhouse gas emissions.

“Houston has a problem,” said Kevin Book, an oil and energy policy analyst with FBR Capital Markets. “But it had a problem anyway.”

During his 34 years representing Los Angeles on Capitol Hill, Waxman championed the Community Right to Know law, which allows local residents to learn what chemical plants are releasing into the air.

He pushed for investigations of the oil companies. And with the start of the Iraq war, Waxman made Halliburton a household name with his relentless criticisms of the company’s multibillion-dollar contracts from the Pentagon.

In a statement by e-mail Thursday evening, Halliburton spokeswoman Cathy Mann said the company believes “the time is right for a fresh start on energy, now that the U.S. campaigns are over.”

Waxman, speaking to reporters after his 137-122 victory in the House Democratic caucus, said his colleagues voted for a change in the committee leadership in hopes of getting action on health care, environmental protection and energy policy.

“We are at a unique moment in history,” said Waxman, who currently is the No. 2 Democrat on the panel. “We have an opportunity that comes only once in a generation.”

House Speaker Nancy Pelosi, D-Calif., made clear what she expects Waxman to accomplish — “progress toward making America energy independent, making health care available to all Americans and addressing the greatest challenge of our time, global warming.”

Dingell, a tireless defender of Detroit’s auto industry, has been the top Democrat on the Energy and Commerce Committee for 28 years. He has been in the House for 52 years, its longest-serving member.

He downplayed the effect the chairmanship change would have on energy policy in the new Congress.

President-elect Barack Obama has called energy “the most important issue that our future economy is going to face,” and Dingell predicted that energy policy will be shaped largely from the White House.

“I think probably what would have emerged either under Dingell or Waxman ... would have been quite similar, because the White House is going to play a major role in setting the energy policy of this country,” Dingell said.

Nonetheless, Waxman is widely expected to be more aggressive than his predecessor in pursuing legislation to curb greenhouse gas emissions — legislation that would affect refineries, petrochemical makers and power plants.

Dingell recently released a “discussion draft” on a bill that would let companies purchase and trade credits for carbon emissions. In general, such arrangements set limits for emissions and allow companies exceeding the caps to buy credits from companies with lower emissions.

But he has clashed with Pelosi and Waxman over California’s rules to limit greenhouse gas emissions from cars and trucks.

‘Troubling sign’

While some cast Waxman as an ideologue — House Republican Leader John Boehner of Ohio called Waxman’s victory a “troubling sign” that Democrats will be “pulled leftward by radical special interests” — environmentalists hailed the news.

“This isn’t about some extreme agenda,” said Steven Biel, global warming campaign director for Greenpeace. “This is about a legislator with a track record of getting things done. America needs to start getting results in terms of clean energy and global warming.”

Rep. Joe Barton of Ennis, who is likely to retain his post as ranking Republican on the committee, vowed to work with Waxman “in a constructive way — when at all possible.”

Industry officials reacted cautiously to Waxman’s victory. “We’re happy to work with whomever is chairman of the committee,” said Judy Penniman, a spokeswoman for the oil industry’s Washington-based trade group, the American Petroleum Institute.

But the oil patch has long expressed its preference with its pocketbook.

Over the last two election cycles, Dingell has received $96,000 from donors in the oil and gas sector and Waxman $2,000, according to the Center for Responsive Politics, which compiles campaign finance data.

“The healing will take time and it will depend on how the victors behave,” said Rep. Gene Green, D-Houston, a Dingell ally who serves as chairman of the panel’s Subcommittee on Environment and Hazardous Materials.